Normalised column densities of the N–H (a), C–H (b), and C=O (c) of crystalline NH₂CHO on CsI at 16 K at low UV fluences (filled black squares). The normalisation factor is the corresponding initial column densities. The best fit to the data (solid red lines) is also shown. The estimated amorphisation rate (σ_a) and the asymptotic transformation (b) for NH₂CHO are also provided.